At least in A14 you can get away with venting into a reasonably large tunnel system (unless you play in a hot biome). Especially if it's connected to the outside with a door. I thought I might be able to heat my hallways that way, but I didn't even notice anything.
I also always build an airlock. And double walls for better insulation, but that's not strictly necessary.
I also always build an airlock. And double walls for better insulation, but that's not strictly necessary.